Research has been underway to develop techniques for analyzing images and directly or indirectly identifying a variety of information included in the images. For example, an image including a face of a person (a face image) may be analyzed to identify the person's gender, age, or facial expressions.
For example, Patent Literature 1 describes an age estimation apparatus that extracts feature quantities from an image and estimates the age of a person based on the feature quantities. More specifically, the age estimation apparatus inputs the feature quantities extracted from the image into its multiclass classifier, which performs classification by age, determines an estimated age using an output from the classifier, and outputs the estimated age.